System for use in treatment of vertebral fractures

ABSTRACT

Methods and devices that displace bone or other hard tissue to create a cavity in the tissue. Where such methods and devices rely on a driving mechanism for providing moving of the device to form a profile that improves displacement of the tissue. These methods and devices also allow for creating a path or cavity in bone for insertion of bone cement or other filler to treat a fracture or other condition in the bone. The features relating to the methods and devices described herein can be applied in any region of bone or hard tissue where the tissue or bone is displaced to define a bore or cavity instead of being extracted from the body such as during a drilling or ablation procedure.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 61/329,220, filed on Apr. 29, 2010, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

This invention relates to medical instruments and systems for creating apath or cavity in vertebral bone to receive bone cement to treat avertebral compression fracture. The features relating to the methods anddevices described herein can be applied in any region of bone or hardtissue where the tissue or bone is displaced to define a bore or cavityinstead of being extracted from the body such as during a drilling orablation procedure. In addition, the present invention also disclosesmethods and devices for ablating or coagulating tissues, including butnot limited to ablating tumor tissue in vertebral and/or cortical bone.

SUMMARY OF THE INVENTION

Methods and devices described herein relate to improved creation of acavity within bone or other hard tissue where the cavity is created bydisplacement of the tissue. In a first example, a method according tothe present disclosure includes treating a vertebral body or other bonestructure. In one variation, the method includes providing an elongatetool having a sharp tip configured for penetration into vertebral bone,the tool having an axis extending from a proximal end to a working endthereof, where the working end comprises at least a first sleeveconcentrically located within a second sleeve and a third sleeve locatedconcentrically about the second sleeve, where each sleeve comprises aseries of slots or notches to limit deflection of the working end to afirst curved configuration in a single plane and where the respectiveseries of slots or notches are radially offset in each sleeve; advancingthe working end through vertebral bone; causing the working end to movefrom a linear configuration to a curved configuration by translating thefirst sleeve relative to the second sleeve in an axial direction; andmoving the working end in the curved configuration within the bone tocreate a cavity therein. Translating of the first sleeve relative to thesecond sleeve can include moving either sleeve or both sleeves in anaxial direction. Additional variations include moving one or bothsleeves in a rotational direction to produce relative axial displacementbetween sleeves.

In an additional variation, the present devices include medicalosteotome devices that can for treat a hard tissue (e.g., in a vertebralbody) by mechanically displacing the hard tissue and/or applyingtherapeutic energy to ablate or coagulate tissue. For example, one suchvariation includes an osteotome type device that is coupled to a powersupply and further includes a handle having an actuating portion and aconnector for electrically coupling the osteotome device to the powersupply; a shaft comprising a first sleeve located concentrically withina second sleeve, the shaft having a distal portion comprising a workingend capable of moving between a linear configuration and an articulatedconfiguration where the articulated configuration is limited to a singleplane, and where each sleeve comprises a series of slots or notches tolimit deflection of the working end to the articulated configuration,where the respective series of slots or notches are radially offset inadjacent sleeves, where a first conductive portion of the shaft iselectrically coupleable to a first pole of the power supply; a sharp tiplocated at a distal tip of the first sleeve of the working end, thesharp tip adapted to penetrate bone within the vertebral body, where thedistal tip is coupleable to a second pole of the power supply, such thatwhen activated, current flows between a portion of the distal tip andthe shaft; a non-conductive layer electrically isolating the firstsleeve from the first conductive portion; and where the shaft and sharptip have sufficient column strength such that application of an impactforce on the handle causes the distal portion of the shaft and thedistal tip to mechanically displace the hard tissue. The power supplycan be coupled to the outer sleeve (either the second or third sleevediscussed herein.)

Another variations of the method disclosed herein can include theapplication of energy between electrodes on the device to ablate tissues(e.g., tumor) or to perform other electrosurgical or mapping procedureswithin the tissue. In one such example for treating a vertebral body,the method can include providing an elongate tool having a sharp tipconfigured for penetration into vertebral bone, the tool having an axisextending from a proximal end to a working end thereof, where theworking end comprises at least a first sleeve concentrically locatedwithin a second sleeve, where each sleeve comprises a series of slots ornotches to limit deflection of the working end to a first curvedconfiguration in a single plane and where the respective series of slotsor notches are radially offset in adjacent sleeves, where a firstconductive portion of the first sleeve is electrically coupled to afirst pole of a power supply; advancing the working end throughvertebral bone; causing the working end to move from a linearconfiguration to a curved configuration by translating the first sleeverelative to the second sleeve in an axial direction; and applying energybetween the first conductive portion and a return electrode electricallycoupled to a second pole of the energy supply to ablate or coagulate aregion within the vertebral body.

In variations of the method, moving the working end to from the linearconfiguration to the curved configuration can include moving the workingend to move through a plurality of curved configurations.

In an additional variation, causing the working end to move from alinear configuration to the curved configuration comprises actuating ahandle mechanism to move the working end from the linear configurationto the curved configuration. The handle mechanism can be moved axiallyand/or rotationally as described herein.

In one variation, actuating of the handle mechanism causes the workingend to move to the first curved configuration without torquing the thirdsleeve.

In additional variations, the working end of the osteotome or tool isspring biased to assume the linear configuration.

The working end can move from the linear configuration to the curvedconfiguration by applying a driving force or impact to the elongate toolwherein penetration in the cortical bone moves the working end from thelinear configuration to the curved configuration. For example, as ahammering or impact force is applied to the working end, the interactionof the sharp tip against bone causes the working end to assume anarticulated and/or curved configuration. Where further axial movement ofthe tool causes compression of the bone and creation of the cavity.

The method can further include the use of one or more cannulae tointroduce the tool into the target region. Such a cannula can maintainthe tool in a straight or linear configuration until the tool advancesout of the cannula or until the cannula is withdrawn from over the tool.

As described herein, upon creation of the cavity, the method can furtherinclude the insertion of a filler material or other substance into thecavity. The filler material can be delivered through the tool or througha separate cannula or catheter.

This disclosure also includes variations of devices for creating acavity within bone or hard tissue. Such variations include devices fortreating a vertebral body or other such structure. In one variation adevice includes a handle having an actuating portion; a shaft comprisinga first sleeve located concentrically within a second sleeve and a thirdsleeve located concentrically about the second sleeve, the shaft havinga distal portion comprising a working end capable of moving between alinear configuration and an articulated configuration where the secondarticulated configuration is limited to a single plane, and where eachsleeve comprises a series of slots or notches to limit deflection of theworking end to the articulated configuration, where the respectiveseries of slots or notches are radially offset in each sleeve; and asharp tip located at a distal tip of the working end, the sharp tipadapted to penetrate vertebral bone within the vertebral body.

In one variation, the devices described herein can include aconfiguration where the first sleeve is affixed to the second sleeve atthe working end such that proximal movement of the first sleeve causesthe working end to assume the articulated configuration. The sleeves canbe affixed at any portion along their length via a mechanical fixationmeans (e.g., a pin or other fixation means), an adhesive, or one or moreweld points. In some variations, fixation of the sleeves occurs at theworking end so that movement of the inner or first sleeve causes theworking end to assume the curved configuration. In some cases, the thirdsleeve can be affixed outside of the working end so long as when thefirst and second sleeves articulate, the third sleeve still articulates.

Devices described herein can optionally include a force-limitingassembly coupled between the actuating portion and the first sleeve suchthat upon reaching a threshold force, the actuating portion disengagesthe first sleeve. In one variation, the force-limiting mechanism isadapted to limit force applied to bone when moving the working end fromthe first configuration toward the second configuration.

In additional variations, devices for creating cavities in bone or hardtissue can include one or more spring elements that extending throughthe first sleeve, where the spring element is affixed to the shaft(within or about either the first, second, or third sleeve). Such springelements cause the working end to assume a linear configuration in arelaxed state.

In additional variations, a device can include an outer or third sleevewhere the slots or notches (that allow deflection) are located on anexterior surface of the third sleeve. The exterior surface is typicallythe surface that faces outward from a direction of the curvedconfiguration. This configuration allows for an interior surface (thesurface located on the interior of the curved portion) to be smooth. Asa result, if the device is withdrawn through tissue or a cannula orother introducer, the smooth surface on the interior of the curveminimizes the chance that the device becomes caught on the opening ofthe cannula or any other structure.

Variations of the device can include one or more lumens that extendthrough the shaft and working end. These lumens can exit at a distal tipof the device or through a side opening in a wall of the device. Thelumen can include a surface comprising a lubricious polymeric material.For example, the material can comprise any bio-compatible materialhaving low frictional properties (e.g., TEFLON®, apolytetrafluroethylene (PTFE), FEP (Fluorinated ethylenepropylene),polyethylene, polyamide, ECTFE (Ethylenechlorotrifluoro-ethylene), ETFE,PVDF, polyvinyl chloride and silicone).

As described herein, the devices can include any number ofconfigurations to prevent rotation between adjacent sleeves but allowaxial movement between the sleeves. For example, the sleeves can bemechanically coupled via a pin/slot or key/keyway configuration. In anadditional variation, the sleeves can be non-circular to preventrotation.

In an additional variation, the disclosure includes various kitscomprising the device described herein as well as a filler material(e.g., a bone cement or other bone filler material).

Variations of the access device and procedures described above includecombinations of features of the various embodiments or combination ofthe embodiments themselves wherever possible.

The methods, devices and systems described herein can be combined withthe following commonly assigned patent applications and provisionalapplications, the entirety of each of which is incorporated by referenceherein: Application No. 61/194,766, filed Sep. 30, 2008; Application No.61/104,380, filed Oct. 10, 2008; Application No. 61/322,281, filed Apr.8, 2010; application Ser. No. 12/571,174 filed Sep. 30, 2009; PCTApplication number PCT/US2009/059113 filed Sep. 30, 2009; applicationSer. No. 12/578,455 filed Oct. 13, 2009.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an osteotome of the invention.

FIG. 2 is a side view of the osteotome of FIG. 1.

FIG. 3 is a cross sectional view of the osteotome of FIG. 1.

FIG. 4 is an enlarged sectional view of the handle of the osteotome ofFIG. 1.

FIG. 5 is an enlarged sectional view of the working end of the osteotomeof FIG. 1.

FIG. 6A is a sectional view of the working end of FIG. 5 in a linearconfiguration.

FIG. 6B is a sectional view of the working end of FIG. 5 in a curvedconfiguration.

FIGS. 7A-7C are schematic sectional views of a method of use of theosteotome of FIG. 1.

FIG. 8 is another embodiment of an osteotome working end.

FIG. 9 is another embodiment of an osteotome working end.

FIG. 10 is another variation of an osteotome with an outer sleeve.

FIG. 11 is a cut-away view of the working end of the osteotome of FIG.10.

FIG. 12A is sectional view of another embodiment of working end, takenalong line 12A-12A of FIG. 11.

FIGS. 12B and 12C illustrate additional variations of preventingrotation between adjacent sleeves.

FIG. 13 is sectional view of another working end embodiment similar tothat of FIG. 11.

FIG. 14 is a cut-away perspective view of the working end of FIG. 13.

FIG. 15 illustrates a variation of an osteotome as described hereinhaving electrodes on a tip of the device and another electrode on theshaft.

FIG. 16 illustrates an osteotome device as shown in FIG. 15 after beingadvanced into the body and where current passes between electrodes.

FIG. 17 illustrates a variation of a device as described herein furtherincluding a connector for providing energy at the working end of thedevice.

FIGS. 18A and 18B illustrate a device having a sharp tip as disclosedherein where the sharp tip is advanceable from the distal end of theshaft.

FIG. 19 shows a cross sectional view of the device illustrated in FIG.18B and also illustrates temperature sensing elements located on device.

FIG. 20 shows a variation of a device where the inner sleeve is extendedfrom the device and where current is applied between the extendedportion of the inner sleeve and the shaft to treat tissue.

FIG. 21 illustrates a variation of a device as described herein furtherincluding an extendable helical electrode carried by the working end ofthe device.

FIGS. 22A and 22B illustrate the device of FIG. 21 with the helicalelectrode in a non-extended position and an extended position.

FIGS. 22C and 22D illustrate charts of variations of electrodes havingablated volumes given a particular duration of an ablation cycle.

FIG. 23 illustrates the working end of the device of FIG. 21 in avertebral body with the helical electrode delivering Rf energy to tissuefor ablation or other treatments.

DETAILED DESCRIPTION

Referring to FIGS. 1-5, an apparatus or osteotome 100 is shown that isconfigured for accessing the interior of a vertebral body and forcreating a pathway in vertebral cancellous bone to receive bone cement.In one embodiment, the apparatus is configured with an extension portionor member 105 for introducing through a pedicle and wherein a workingend 110 of the extension member can be progressively actuated to curve aselected degree and/or rotated to create a curved pathway and cavity inthe direction of the midline of the vertebral body. The apparatus can bewithdrawn and bone fill material can be introduced through a bone cementinjection cannula. Alternatively, the apparatus 100 itself can be usedas a cement injector with the subsequent injection of cement through alumen 112 of the apparatus.

In one embodiment, the apparatus 100 comprises a handle 115 that iscoupled to a proximal end of the extension member 105. The extensionmember 105 comprises an assembly of first (outer) sleeve 120 and asecond (inner) sleeve 122, with the first sleeve 120 having a proximalend 124 and distal end 126. The second sleeve 122 has a proximal end 134and distal end 136. The extension member 105 is coupled to the handle115, as will be described below, to allow a physician to drive theextension member 105 into bone while contemporaneously actuating theworking end 110 into an actuated or curved configuration (see FIG. 6).The handle 115 can be fabricated of a polymer, metal or any othermaterial suitable to withstand hammering or impact forces used to drivethe assembly into bone (e.g., via use of a hammer or similar device onthe handle 115). The inner and outer sleeves are fabricated of asuitable metal alloy, such as stainless steel or NiTi. The wallthicknesses of the inner and outer sleeves can range from about 0.005″to 0.010″ with the outer diameter the outer sleeve ranging from about2.5 mm to 5.0 mm.

Referring to FIGS. 1, 3 and 4, the handle 115 comprises both a firstgrip portion 140 and a second actuator portion indicated at 142. Thegrip portion 140 is coupled to the first sleeve 120 as will be describedbelow. The actuator portion 142 is operatively coupled to the secondsleeve 122 as will be described below. The actuator portion 142 isrotatable relative to the grip portion 140 and one or more plastic flextabs 145 of the grip portion 140 are configured to engage notches 146 inthe rotatable actuator portion 142 to provide tactile indication andtemporary locking of the handle portions 140 and 142 in a certain degreeof rotation. The flex tabs 145 thus engage and disengage with thenotches 146 to permit ratcheting (rotation and locking) of the handleportions and the respective sleeve coupled thereto.

The notches or slots in any of the sleeves can comprise a uniform widthalong the length of the working end or can comprise a varying width.Alternatively, the width can be selected in certain areas to effectuatea particular curved profile. In other variation, the width can increaseor decrease along the working end to create a curve having a varyingradius. Clearly, it is understood that any number of variations arewithin the scope of this disclosure.

FIG. 4 is a sectional view of the handle showing a mechanism foractuating the second inner sleeve 122 relative to the first outer sleeve120. The actuator portion 142 of the handle 115 is configured with afast-lead helical groove indicated at 150 that cooperates with aprotruding thread 149 of the grip portion 140 of the handle. Thus, itcan be understood that rotation of the actuation portion 142 will movethis portion to the position indicated at 150 (phantom view). In oneembodiment, when the actuator portion 142 is rotated a selected amountfrom about 45° to 720°, or from about 90° to 360°, the inner sleeve 122is lifted proximally relative to the grip portion 140 and outer sleeve120 to actuate the working end 110. As can be seen in FIG. 4 theactuator portion 142 engages flange 152 that is welded to the proximalend 132 of inner sleeve 122. The flange 152 is lifted by means of a ballbearing assembly 154 disposed between the flange 152 and metal bearingsurface 155 inserted into the grip portion 140 of the handle. Thus, therotation of actuator 142 can lift the inner sleeve 122 without creatingtorque on the inner sleeve.

Now turning to FIGS. 5, 6A and 6B, it can be seen that the working end110 of the extension member 105 is articulated by cooperating slottedportions of the distal portions of outer sleeve 120 and inner sleeve 122that are both thus capable of bending in a substantially tight radius.The outer sleeve 120 has a plurality of slots or notches 162 thereinthat can be any slots that are perpendicular or angled relative to theaxis of the sleeve. The inner sleeve 122 has a plurality of slots ornotches indicated at 164 that can be on an opposite side of the assemblyrelative to the slots 162 in the outer sleeve 120. The outer and innersleeves are welded together at the distal region indicated at weld 160.It thus can be understood that when inner sleeve 122 is translated inthe proximal direction, the outer sleeve will be flexed as depicted inFIG. 6B. It can be understood that by rotating the actuator handleportion 142 a selected amount, the working end can be articulated to aselected degree.

FIGS. 4, 5, 6A and 6B further illustrate another element of theapparatus that comprises a flexible flat wire member 170 with a proximalend 171 and flange 172 that is engages the proximal side of flange 152of the inner sleeve 122. At least the distal portion 174 of the flatwire member 170 is welded to the inner sleeve at weld 175. This flatwire member thus provides a safety feature to retain the working end inthe event that the inner sleeve fails at one of the slots 164.

Another safety feature of the apparatus comprises a torque limiter andrelease system that allows the entire handle assembly 115 to freelyrotate—for example if the working end 110 is articulated, as in FIG. 6B,when the physician rotates the handle and when the working end isengaged in strong cancellous bone. Referring to FIG. 4, the grip portion142 of the handle 115 engages a collar 180 that is fixed to a proximalend 124 of the outer sleeve 120. The collar 180 further comprisesnotches 185 that are radially spaced about the collar and are engaged bya ball member 186 that is pushed by a spring 188 into notches 185. At aselected force, for example a torque ranging from greater than about 0.5inch*lbs but less that about 7.5 inch*lbs, 5.0 inch*lbs or 2.5 inch*lbs,the rotation of the handle 115 overcomes the predetermined limit. Whenthe torque limiter assembly is in its locked position, the ball bearing186 is forced into one of the notches 185 in the collar 180. When toomuch torque is provided to the handle and outer sleeve, the ball bearing186 disengages the notch 185 allowing the collar 180 to turn, and thenreengages at the next notch, releasing anywhere from 0.5 inch*lbs to 7.5inch*lbs of torque.

Referring to FIGS. 6A and 6B, it can be understood that the inner sleeve122 is weakened on one side at its distal portion so as to permit theinner sleeve 122 to bend in either direction but is limited by thelocation of the notches in the outer sleeve 120. The curvature of anyarticulated configuration is controlled by the spacing of the notches aswell as the distance between each notch peak. The inner sleeve 122 alsohas a beveled tip for entry through the cortical bone of a vertebralbody. Either the inner sleeve or outer sleeve can form the distal tip.

Referring to FIGS. 7A-7C, in one variation of use of the device, aphysician taps or otherwise drives a stylet 200 and introducer sleeve205 into a vertebral body 206 typically until the stylet tip 208 iswithin the anterior ⅓ of the vertebral body toward cortical bone 210(FIG. 7A). Thereafter, the stylet 200 is removed and the sleeve 205 ismoved proximally (FIG. 7B). As can be seen in FIG. 7B, the tool orosteotome 100 is inserted through the introducer sleeve 205 andarticulated in a series of steps as described above. The working end 110can be articulated intermittently while applying driving forces andoptionally rotational forces to the handle 115 to advance the workingend through the cancellous bone 212 to create path or cavity 215. Thetool is then tapped to further drive the working end 110 to, toward orpast the midline of the vertebra. The physician can alternativelyarticulate the working end 110, and drive and rotate the working endfurther until imaging shows that the working end 100 has created acavity 215 of an optimal configuration. Thereafter, as depicted in FIG.7C, the physician reverses the sequence and progressively straightensthe working end 110 as the extension member is withdrawn from thevertebral body 206. Thereafter, the physician can insert a bone cementinjector 220 into the path or cavity 215 created by osteotome 100. FIG.7C illustrates a bone cement 222, for example a PMMA cement, beinginjected from a bone cement source 225.

In another embodiment (not shown), the apparatus 100 can have a handle115 with a Luer fitting for coupling a bone cement syringe and the bonecement can be injected through the lumen 112 of the apparatus. In suchan embodiment FIG. 9, the lumen can have a lubricious surface layer orpolymeric lining 250 to insure least resistance to bone cement as itflows through the lumen. In one embodiment, the surface or lining 250can be a fluorinated polymer such as TEFLON® or polytetrafluroethylene(PTFE). Other suitable fluoropolymer resins can be used such as FEP andPFA. Other materials also can be used such as FEP (Fluorinatedethylenepropylene), ECTFE (Ethylenechlorotrifluoro-ethylene), ETFE,Polyethylene, Polyamide, PVDF, Polyvinyl chloride and silicone. Thescope of the invention can include providing a polymeric material havinga static coefficient of friction of less than 0.5, less than 0.2 or lessthan 0.1.

FIG. 9 also shows the extension member or shaft 105 can be configuredwith an exterior flexible sleeve indicated at 255. The flexible sleevecan be any commonly known biocompatible material, for example, thesleeve can comprise any of the materials described in the precedingparagraph.

As also can be seen in FIG. 9, in one variation of the device 100, theworking end 110 can be configured to deflect over a length indicated at260 in a substantially smooth curve. The degree of articulation of theworking end 100 can be at least 45°, 90°, 135° or at least 180° asindicated at 265 (FIG. 9). In additional variations, the slots of theouter 120 and inner sleeves 120 can be varied to produce a device havinga radius of curvature that varies among the length 260 of the device100.

In another embodiment of the invention, the inner sleeve can be springloaded relative the outer sleeve, in such a way as to allow the workingend to straighten under a selected level of force when pulled in alinear direction. This feature allows the physician to withdraw theassembly from the vertebral body partly or completely without furtherrotation the actuating portion 142 of handle 115. In some variations,the force-limiter can be provided to allow less than about 10 inch*lbsof force to be applied to bone.

In another embodiment shown in FIG. 8, the working end 110 is configuredwith a tip 240 that deflects to the position indicated at 240′ whendriven into bone. The tip 240 is coupled to the sleeve assembly byresilient member 242, for example a flexible metal such as stainlesssteel or NiTi. It has been found that the flexing of the tip 240 causesits distal surface area to engage cancellous bone which can assist indeflecting the working end 110 as it is hammered into bone.

In another embodiment of the invention (not shown), the actuator handlecan include a secondary (or optional) mechanism for actuating theworking end. The mechanism would include a hammer-able member with aratchet such that each tap of the hammer would advance assembly andprogressively actuate the working end into a curved configuration. Aratchet mechanism as known in the art would maintain the assembly ineach of a plurality of articulated configurations. A release would beprovided to allow for release of the ratchet to provide forstraightening the extension member 105 for withdrawal from the vertebralbody.

FIGS. 10 and 11 illustrate another variation of a bone treatment device400 with a handle 402 and extension member 405 extending to working end410 having a similar construction to that FIGS. 1 to 6B. The device 400operates as described previously with notched first (outer) sleeve 120and cooperating notched second (inner) sleeve 122. However, thevariation shown in FIGS. 10 and 11 also includes a third concentricnotched sleeve 420, exterior to the first 120 and second 122 sleeves.The notches or slots in sleeve 420 at the working end 410 permitdeflection of the sleeve as indicated at 265 in FIG. 11.

FIG. 10 also illustrates the treatment device 400 as including a luerfitting 412 that allows the device 402 to be coupled to a source of afiller material (e.g., a bone filler or bone cement material). The luercan be removable from the handle 402 to allow application of an impactforce on the handle as described above. Moreover, the luer fitting 402can be located on the actuating portion of the handle, the stationarypart of the handle or even along the sleeve. In any case, variations ofthe device 400 permit coupling the filler material with a lumenextending through the sleeves (or between adjacent sleeves) to depositfiller material at the working end 410. As shown by arrows 416, fillermaterial can be deposited through a distal end of the sleeves (where thesharp tip is solid) or can be deposited through openings in a side-wallof the sleeves. Clearly, variations of this configuration are within thescope of those familiar in the field.

In some variations, the third notched sleeve 420 is configured with itssmooth (non-notched) surface 424 disposed to face inwardly on thearticulated working end (FIG. 11) such that a solid surface forms theinterior of the curved portion of the working end 410. The smoothsurface 424 allows withdrawal of the device 110 into a cannula orintroducer 205 without creating a risk that the slots or notches becomecaught on a cannula 205 (see e.g., FIG. 7B).

As shown in FIGS. 10-11, the third (outermost) sleeve 420 can extendfrom an intermediate location on the extension member 405 to a distalend of the working end 410. However, variations of the device includethe third sleeve 420 extending to the handle 402. However, the thirdsleeve 420 is typically not coupled to the handle 402 so that anyrotational force or torque generated by the handle 402 is not directlytransmitted to the third sleeve 420.

In one variation, the third sleeve 420 is coupled to the second sleeve120 at only one axial location. In the illustrated example shown in FIG.11, the third sleeve 420 is affixed to second sleeve 420 by welds 428 atthe distal end of the working end 410. However, the welds or otherattachment means (e.g., a pin, key/keyway, protrusion, etc.) can belocated on a medial part of the sleeve 420. The sleeve 420 can befabricated of any bio-compatible material. For example, in onevariation, the third sleeve is fabricated form a 3.00 mm diameterstainless steel material with a wall thickness of 0.007″. The first,second and third sleeves are sized to have dimensions to allow a slidingfit between the sleeves.

FIG. 12A is a sectional view of extension member 405 of anothervariation, similar to that shown in FIGS. 10-11. However, the variationdepicted by FIG. 12A comprises non-round configurations of concentricslidable sleeves (double or triple sleeve devices). This configurationlimits or prevents rotation between the sleeves and allows the physicianto apply greater forces to the bone to create a cavity. While FIG. 12Aillustrates an oval configuration, any non-round shape is within thescope of this disclosure. For example, the cross-sectional shape cancomprise a square, polygonal, or other radially keyed configuration asshown in FIGS. 12B and 12C. As shown in FIG. 12C the sleeves can includea key 407 and a receiving keyway 409 to prevent rotation but allowrelative or axial sliding of the sleeves. The key can comprise anyprotrusion or member that slides within a receiving keyway. Furthermore,the key can comprise a pin or any raised protrusion on an exterior orinterior of a respective sleeve. In this illustration, only the first122 and second 120 sleeves are illustrated. However, any of the sleevescan be configured with the key/keyway. Preventing rotation betweensleeves improves the ability to apply force to bone at the articulatedworking end.

FIGS. 13-14 illustrate another variation of a working end 410 of anosteotome device.

In this variation, the working end 410 includes one or more flat springelements 450, 460 a, 460 b, 460 c, 460 d, that prevent relative rotationof the sleeves of the assembly thus allowing greater rotational forcesto be applied to cancellous bone from an articulated working end. Thespring elements further urge the working end assembly into a linearconfiguration. To articulate the sleeves, a rotational force is appliedto the handle as described above, once this rotational force is removed,the spring elements urge the working end into a linear configuration. Asshown in FIG. 13, one or more of the spring elements can extend throughthe sleeves for affixing to a handle to prevent rotation. Furthermore,the distal end 454 of flat spring element 450 is fixed to sleeveassembly by weld 455. Thus, the spring element is fixed at each end toprevent its rotation. Alternate variations include one or more springelements being affixed to the inner sleeve assembly at a medial sectionof the sleeve.

As shown in FIGS. 13-14, variations of the osteotome can include anynumber of spring elements 460 a-460 d. These additional spring elements460 a-460 d can be welded at either a proximal or distal end thereof toan adjacent element or a sleeve to allow the element to function as aleaf spring.

In an additional variation, the osteotome device can include one or moreelectrodes 310, 312 as shown in FIG. 15. In this particular example, thedevice 300 includes spaced apart electrodes having opposite polarity tofunction in a bi-polar manner. However, the device can include amonopolar configuration. Furthermore, one or more electrodes can becoupled to individual channels of a power supply so that the electrodescan be energized as needed. Any variation of the device described abovecan be configured with one or more electrodes as described herein.

FIG. 16 illustrates an osteotome device 300 after being advanced intothe body as discussed above. As shown by lines 315 representing currentflow between electrodes, when required, the physician can conduct RFcurrent between electrodes 310 and 312 to apply coagulative or ablativeenergy within the bone structure of the vertebral body (or other hardtissue). While FIG. 16 illustrates RF current 315 flow betweenelectrodes 310 and 312, variations of the device can include a number ofelectrodes along the device to apply the proper therapeutic energy.Furthermore, an electrode can be spaced from the end of the osteotomerather than being placed on the sharp tip as shown by electrode 310. Insome variations, the power supply is coupled to the inner sharp tip orother working end of the first sleeve. In those variations with only twosleeves, the second pole of the power supply is coupled with the secondsleeve (that is the exterior of the device) to form a return electrode.However, in those variations having three sleeves, the power supply canalternatively be coupled with the third outer sleeve. In yet additionalvariations, the second and third sleeves can both function as returnelectrodes. However, in those devices that are monopolar, the returnelectrode will be placed outside of the body on a large area of skin

FIGS. 17 to 20 illustrate another variation of an articulating probe orosteotome device 500. In this variation, the device 500 includes aworking end 505 that carries one or more RF electrodes that can be usedto conduct current therethrough. Accordingly, the device can be used tosense impedance of tissue, locate nerves, or simply applyelectrosurgical energy to tissue to coagulate or ablate tissue. In onepotential use, the device 500 can apply ablative energy to a tumor orother tissue within the vertebra as well as create a cavity.

FIGS. 17, 18A, 18B and 19, illustrate a variation of the device 500 ashaving a handle portion 506 coupled to a shaft assembly 510 that extendsalong axis 512 to the articulating working end 505. The articulatingworking end 505 can be actuatable as described above. In addition, FIG.17 shows that handle component 514 a can be rotated relative to handlecomponent 514 b to cause relative axial movement between a first outersleeve 520 and second inner sleeve 522 (FIG. 19) to cause the slottedworking ends of the sleeve assembly to articulate as described above.The working end 505 of FIG. 19 shows two sleeves 520 and 522 that areactuatable to articulate the working end, but it should be appreciatedthat a third outer articulating sleeve can be added as depicted above.In one variation, the articulating working end can articulate 90° byrotating handle component 514 a between ¼ turn and ¾ turn. The rotatinghandle component 514 a can include detents at various rotationalpositions to allow for controlled hammering of the working end intobone. For example, the detents can be located at every 45° rotation orcan be located at any other rotational increment.

FIG. 17 depict an RF generator 530A and RF controller 530B connectableto an electrical connector 532 in the handle component 514 a with a plugconnector indicated at 536. The RF generator is of the type known in theart for electrosurgical ablation. The outer sleeve 520 comprises a firstpolarity electrode indicated at 540A (+). However, any energy modalitycan be employed with the device.

FIGS. 18A and 18B illustrate yet another variation of a working end of adevice for creating cavities in hard tissue. As shown, the device 500can include a central extendable sleeve 550 with a sharp tip 552 that isaxially extendable from passageway 554 of the assembly of first andsecond sleeves 520 and 522 (FIG. 19). The sleeve 550 can also include asecond polarity electrode indicated at 540B (−). Clearly, the first andsecond electrodes will be electrically insulated from one another. Inone variation, and as shown in FIG. 19, the sleeve assembly can carry athin sleeve 555 or coating of an insulative polymer such as PEEK toelectrically isolate the first polarity electrode 540A (+) from thesecond polarity electrode 540B (−). The electrode can be deployed byrotating knob 558 on the striking surface of handle component 514 a(FIG. 17). The degree of extension of central sleeve 550 can optionallybe indicated by a slider tab 557 on the handle. In the illustratedvariation, the slider tab is located on either side of handle component514 a (FIG. 17). Sleeve 550 can be configured to extend distally beyondthe assembly of sleeves 520 and 522 a distance of about 5 to 15 mm.

Referring to FIG. 19, the central extendable sleeve 550 can have aseries of slots in at least a distal portion thereof to allow it to bendin cooperation with the assembly of first and second sleeves 520 and522. In the embodiment shown in FIG. 18B, the central sleeve 550 canoptionally include a distal portion that does not contain any slots.However, additional variations include slots on the distal portion ofthe sleeve.

FIG. 19 further depicts an electrically insulative collar 560 thatextends length A to axially space apart the first polarity electrode540A (+) from the second polarity electrode 540B (−). The axial length Acan be from about 0.5 to 10 mm, and usually is from 1 to 5 mm. Thecollar can be a ceramic or temperature resistant polymer.

FIG. 19 also depicts a polymer sleeve 565 that extends through the lumenin the center of electrode sleeve 550. The polymer sleeve 565 canprovide saline infusion or other fluids to the working end and/or beused to aspirate from the working end when in use. The distal portion ofsleeve 550 can include one or more ports 566 therein for deliveringfluid or aspirating from the site.

In all other respects, the osteotome system 500 can be driven into boneand articulated as described above. The electrodes 540A and 540B areoperatively coupled to a radiofrequency generator as is known in the artfor applying coagulative or ablative electrosurgical energy to tissue.In FIG. 20, it can be seen that RF current 575 is indicated in pathsbetween electrodes 540A and 540B as shown by lines 575. RF generator530A and controller 530B for use with the devices described herein caninclude any number of power settings to control the size of targetedcoagulation or ablation area. For example, the RF generator andcontroller can have Low (5 watts), medium (15 Watts) and High (25 watts)power settings. The controller 530B can have a control algorithm thatmonitors the temperature of the electrodes and changes the power inputin order to maintain a constant temperature. At least one temperaturesensing element (e.g., a thermocouple) can be provided on variousportions of the device. For example, and as shown in FIG. 19, atemperature sensing element 577 can be provided at the distal tip ofsleeve 550 tip while a second temperature sensing element 578 can beprovided proximal from the distal tip to provide temperature feedback tothe operator to indicate the region of ablated tissue during theapplication of RF energy. In one example, the second temperature sensingelement was located approximately 15 to 20 mm from the distal tip.

FIG. 21 illustrates another variation of articulating osteotome 600 withRF ablation features. Variations of the illustrated osteotome 600 can besimilar to the osteotome of FIGS. 17-18B. In this variation, theosteotome 600 has a handle 602 coupled to shaft assembly 610 asdescribed above. The working end 610 again has an extendable assemblyindicated at 615 in FIG. 21 that can be extended by rotation of handleportion 622 relative to handle 602. The osteotome can be articulated asdescribed previously by rotating handle portion 620 relative to handle602.

FIGS. 22A-22B are views of the working end 610 of FIG. 21 in a firstnon-extended configuration (FIG. 22A) and a second extendedconfiguration (FIG. 22B). As can be seen in FIGS. 22A-22B, the extensionportion 615 comprises an axial shaft 624 together with a helical springelement 625 that is axially collapsible and extendible. In oneembodiment, the shaft can be a tube member with ports 626 fluidlycoupled to a lumen 628 therein. In some variations, the ports can carrya fluid to the working end or can aspirate fluid from the working end.

In FIGS. 22A-22B, it can be seen that axial shaft 624, helical springelement 625 together with sharp tip 630 comprise a first polarityelectrode (+) coupled to electrical source 530A and controller 530B asdescribed previously. An insulator 632 separates the helical spring 625electrode from the more proximal portion of the sleeve which comprisesopposing polarity electrode 640 (−). The RF electrodes can function asdescribed above (see FIG. 20) to ablate tissue or otherwise deliverenergy to tissue.

In one variation, the extension portion 615 can extend from a collapsedspring length of 2 mm, 3 mm, 4 mm or 5 mm to an extended spring lengthof 6 mm, 7 mm, 8 mm, 9 mm 10 mm or more. In the working end embodiment615 in FIG. 22B, the spring can comprise a flat rectangular wire thatassists in centering the spring 625 about shaft 624 but still cancollapse to short overall length, with the flat surfaces of rectangularwire oriented for stacking. However, other variations are within thescope of the variations described herein.

The use of the spring 625 as an electrode provides significantimprovements in delivering energy. This spring provides (i) greatlyincreased electrode surface area and (ii) a very greatly increasedlength of relatively sharp edges provided by the rectangular wire—whichprovides for edges. Because the edges provide low surface area theconcentration or density of RF current is greater at the edges andallows for theh RF current to jump or arc. Both these aspects of theinvention—increased electrode surface area and increased electrode edgelength—allow for much more rapid tissue ablation.

In one aspect of the invention, the surface area of the spring electrode625 can be at least 40 mm², at least 50 mm², or at least 60 mm² over thespring electrode lengths described above.

In another aspect of the invention, the total length of the 4 edges ofrectangular wire spring can be greater than 50 mm, greater than 100 mmor greater than 150 mm over the spring electrode lengths describedabove.

In one example used in testing, an osteotome 600 (as in FIG. 21-22B) wasconfigured with a helical spring that had a collapsed length of 1.8 mmand an extended length of 7.5 mm. In this embodiment, the surface areaof the spring electrode 625 when extended was 64.24 mm² and the totallength of the electrodes edges was 171.52 mm (four edges at 42.88 mm peredge).

In a comparison test, a first osteotome without a helical electrode wascompared against a second osteotome 600 with a helical electrode as inFIG. 22B. These devices were evaluated at different power levels anddifferent energy delivery intervals to determine volume of ablation. Theworking ends of the devices had similar dimensions excepting for thehelical spring electrode. Referring to FIG. 22C, RF energy was deliveredat a low power setting of 5 Watts. It can be seen in FIG. 22C that at atreatment interval of 120 seconds and 5 W, the volume of ablation wasabout 3 times faster with the helical electrode compared to the workingend without the helical electrode (1.29 cc vs. 0.44 cc).

Another comparison test of the same first osteotome 500 (FIG. 18B) andsecond osteotome 600 with a helical electrode (FIG. 22B) were evaluatedat higher 15 Watt power level. As can be seen in FIG. 22D, RF energy ata treatment interval of 25 seconds and 15 W, the volume of ablation wasagain was about 3 times faster with the helical electrode compared tothe working end without the helical electrode (1.00 cc vs. 0.37 cc).Referring to FIG. 22D, the device without the helical electrode impededout before 60 seconds passed, so that data was not provided. The testingshows that the helical electrode is well suited for any type of tissueor tumor ablation, with a 60 second ablation resulting in 1.63 cc ofablated tissue.

FIG. 23 schematically illustrates the osteotome 600 in use in avertebral body, wherein the RF current between the electrodes 625 and640 ablate a tissue volume indicated at 640.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

1. A medical osteotome device for treating a vertebral body, comprising:a handle having a connector for electrically coupling the osteotomedevice to a power supply; a shaft extending from the handle to a workingend, where a first conductive portion of the shaft is electricallycoupleable to a first pole of the power supply; and an extendableelement extendible from the shaft; where the extendable element iscoupleable to a second pole of the power supply, such that whenactivated, current flows between the extendable element and the shaft.2. The medical device of claim 1, where wherein the extendable elementhas an electrode surface area of at least 40 mm2.
 3. The medical deviceof claim 1, where extendable element includes a helical electrode. 4.The medical device of claim 1, wherein an actuation portion isconfigured to deform the working end into an articulated configuration.5. The medical device of claim 1, where the handle is configured toreceive an impact force to causes the working end to penetrate bone. 6.The medical device of claim 1, further comprising a lumen extendingthrough the shaft and working end.
 7. A medical osteotome device fortreating a vertebral body, comprising: a handle having a connector forelectrically coupling the osteotome device to a power supply; a shaftextending from the handle to a working end, where a first conductiveportion of the shaft is electrically coupleable to a first pole of thepower supply; and an extendable element extendible from the shaft; wherethe extendable element is coupleable to a second pole of the powersupply, such that when activated, current flows between the extendableelement and the shaft.
 8. The medical device of claim 7, wherein theextendable element has a total length of electrode edges of greater than50 mm.
 9. The medical device of claim 7, where extendable elementincludes a helical electrode.
 10. A medical device for ablating tissue,comprising: an elongated probe having a handle end and a working end; anextendable helical element comprising an electrode carried by theworking end, wherein the helical element is moveable from an axiallynon-extended position to an axially extended position to provide anincreased electrode surface area.
 11. The medical device of claim 10,where the helical electrode is formed form a flat wire.
 12. The medicaldevice of claim 10, where the helical electrode is formed form arectangular wire.
 13. The medical device of claim 10, where the helicalelectrode has a non-extended length of less than 5 mm.
 14. The medicaldevice of claim 10, where the helical electrode has an extended lengthof greater than 6 mm.
 15. The medical device of claim 10, where theworking end is articulatable.
 16. The medical device of claim 10,wherein the handle carries an actuation mechanism configured to deformthe working end into an articulated configuration.
 17. The medicaldevice of claim 10, wherein the extendable element has an electrodesurface area of at least at least 60 mm².
 18. The medical device ofclaim 10, wherein the extendable element has a total length of electrodeedges of greater than 50 mm.